(1) Field of the Invention
This invention relates to alkaline scouring baths useful for removing impurities from textiles and to a process for so treating such textiles. More particularly, this invention relates to alkaline scouring baths containing as a cleaning agent a mixture of nonionic surfactant and certain polycarboxylic acids or salts thereof.
(2) The Prior Art
Textiles, especially natural cellulosic fibers such as cotton, contain impurities that adhere to the fibers, such as processing chemicals, residues of the ginning process like seed husks, leaves, shives and the like, natural fats and waxes, collenchymatous, lignin, and pectin. Removing these impurities prior to dyeing is desirable to prevent dark colored particules in the fabric and uneven dyeing. The impurities are removed from a majority of the fibers produced and the process is referred to as scouring. Scouring is frequently used in combination with bleaching. Scouring may be carried out on loose fibers, slivers, yarn or fabrics; but for ease of handling, fabric form is to be preferred. For example, surgical cotton is scoured and bleached as raw stock; whereas, yarn for dyeing is bleached, for example, in packages. Piece goods are generally scoured and bleached in rope form because it is cheaper to operate in this way; certain types, however, require treatment in open width.
Scouring, as used herein, means the use of soaps, detergents and alkalies to remove naturally occurring waxes and soils, oils, and protective agents applied to facilitate processing, as well as accidental contamination by mill greases and dirt, from fibers, yarns and fabrics, i.e., textiles.
In the scouring process the soil is separated from the textile and dissolved, dispersed or emulsified in the cleaning solution and kept from being redeposited onto the fiber. The soil is removed by its solubility in water or, if it is insoluble, by a process of emulsification or dispersion in the detergent solution. There may be chemical reactions with any particular class of soil in order to render it water soluble or dispersible.
Both soaps and synthetic detergents are used as surface-active agents in scouring processes. These products reduce the surface tension of water and enable the water to wet the textile fibers more rapidly and uniformly. These products also provide the emulsifying and dispersing action needed for the removal of soil. Up to about 1930, soaps were the only satisfactory detergents known and used. However, there were serious limitations on their use because of their inability to function in acid media and in the presence of heavy-metal ions. The development of synthetic detergents has provided versatile surface-active compounds suitable for use under a wide variety of conditions, including the presence of acids, alkalies and a number of metal salts that precipitate soap. Synthetic detergents are highly effective when compared to soap, and replace soaps because they eliminate the possibility of soap deposits which frequently are a cause of imperfections in dyeing and finishing. Many of the more efficient ones are, however, expensive and do not have efficient wetting ability.
It is, therefore, an object of this invention to provide an alkaline scouring bath that will effectively clean natural cellulose fibers while rapidly wetting the fibers.
Another object of this invention is to provide a process for using the alkaline textile scouring bath.
Still another object of this invention is to provide a process for scouring textiles that not only cleans the textiles but also does not cause any substantial damage to the fibers.
Other objects, features and advantages of this invention will become apparent from the following detailed description.